[Leetcode]187. Repeated DNA Sequences

📄 Description

The DNA sequence is composed of a series of nucleotides abbreviated as 'A', 'C', 'G', and 'T'.

For example, "ACGAATTCCG" is a DNA sequence.
When studying DNA, it is useful to identify repeated sequences within the DNA.

Given a string s that represents a DNA sequence, return all the 10-letter-long sequences (substrings) that occur more than once in a DNA molecule. You may return the answer in any order.

Example 1:

Input: s = "AAAAACCCCCAAAAACCCCCCAAAAAGGGTTT"
Output: ["AAAAACCCCC","CCCCCAAAAA"]

Example 2:

Input: s = "AAAAAAAAAAAAA"
Output: ["AAAAAAAAAA"]

Constraints:

• 1 <= s.length <= 105
• s[i] is either 'A', 'C', 'G', or 'T'.

💻 My Submission

class Solution:
    def findRepeatedDnaSequences(self, s: str) -> List[str]:
        
        _dict=defaultdict(int)
        
        for i in range(len(s)-9):
            _dict[s[i:i+10]]+=1
        
        return [x for x in _dict if _dict[x]>1]

🕐 Complexity

Time Complexity: O(n)
Space Complexity: O(1)

References

• https://leetcode.com/problems/repeated-dna-sequences/